1. Field of the Invention
The present invention is directed to motorcycles, and in particular, to a rear brake assembly for a motorcycle.
2. Background of the Invention
Conventional motorcycles include front and rear brakes. Often, these brakes are in the form of disk brakes mounted to the respective front and rear axles. Specifically, rear brake assemblies generally include a rear disk mounted to a rear axle. The rear disk rotates with the rear wheel. Calipers or other devices apply a braking force to the rear disk brake, which in turn, provides a braking force to the rear wheel.
Most of the braking on a motorcycle is done by the front disk brake. It has been estimated that from 60% to 80% of the braking is done by the front wheel. Also, it is typical for the front disk brake to be applied using a hand lever disposed on a handle bar and operated by a rider's hand. In contrast, the rear disk brake is typically applied by using a brake pedal operated by one of the rider's feet.
This braking arrangement can make proper braking of the rear wheel difficult. Because the majority of the braking is done by the front wheel, very little force is required to brake the rear wheel. Because of this, the rear wheel can be locked up easily during braking. This lock up problem is compounded by the fact that the rider must brake the rear wheel with the rider's foot as opposed to the rider's hand. Riders generally find their feet less sensitive and more difficult to precisely control than their hands. A braking system that provides better brake feel and more precise control is needed.
On conventional motorcycles, rear brakes are disposed coaxial with the rear wheel. In other words, the rear brake, be it a disk or drum, shares the same axis of rotation as the rear wheel. In this conventional design, the rear brake assembly moves with the rear wheel. All of the bumps and all of the vibrations experienced by the rear wheel is also experienced by the rear brake assembly. Because of this, braking on bumpy or uneven surfaces can be difficult because the vibration of the rear brake assembly can interfere with brake feel and make it difficult to properly modulate the braking force on the rear wheel.
Also, because conventional rear brake assemblies are mounted coaxially with the rear wheel, the weight or mass of the rear brake assembly is unsprung weight. Any increase in unsprung weight is not desirable and is detrimental to a vehicle's dynamics, balance and handling characteristics.